Science / Medicine : Ultraviolet Radiation Rise Likely to Affect Crop Yields

Ultraviolet radiation streaming through holes in the atmosphere’s ozone layer could raise or lower crop yields by tipping the balance of competition between crops and weeds, according to Paul W. Barnes of Southwest Texas State University in San Marcos.

The ozone layer absorbs much of the sun’s ultraviolet radiation, particularly the so-called ultraviolet-B radiation, or UV-B, that is especially dangerous to plants and animals.

UV-B radiation is known to damage plants in a variety of ways, often acting directly on plant genetic material. New studies suggest that UV-B also can tip fragile ecosystem balances, causing indirect damage to plants in ways hard to predict, Barnes said.

“One may only see the effect of UV-B radiation when we have a crop growing in competition with weeds,” he said. Barnes found that increases in UV-B radiation allowed wheat to do a better job of outgrowing a weed called wild oats. The weed is a chronic pest in wheat fields and grows more slowly under increased UV-B radiation. In that case, an increase in radiation helps the crop at the expense of the weeds.

In other cases, though, weeds may be able to compete better against crops, Barnes said. But scientists have so far been unable to predict which crops are likely to compete better against weeds under increased UV-B radiation and which are likely to do worse, he added.